Why breaking the link between two list nodes when partitioning a list?

I was trying to solve the Partition List problem on LeetCode. The problem asks to sort an linked list given a target list node, so that all the list nodes having smaller value than the target will come before the target, while their original relative order remains unchanged.

I was able to come up a straightforward algorithm and to pass the online judge, basically creating two pointers and using them each to link either nodes